Small man syndrome really does exist, US government scientists have found, after research showed men who feel the least masculine are at risk of committing violent acts.

Although it is traditionally supposed that 'macho' men are the most prone to acts of aggression, in fact outsiders who feel that they do not fit gender stereotypes are equally as dangerous.

Sometimes called the Napoleon complex, small man syndrome supposes that men who feel the least masculine seek power, war and conquest to make up for their physical shortcomings.

Researchers at the Federal Centres for Disease Control in Atlanta, Georgia, say men can suffer from 'male discrepancy stress' where they feel they are falling short of traditional masculine gender norms. And it appears to make them more prone to violence than men who feel comfortable in their own skin.

Crime

They analysed responses of 600 US men aged between 18 and 50 in 2012 to an online survey about their perceptions of male gender, their own self-image, and behaviour such as drug taking, violence and crime.

The men who considered themselves less masculine than average and who experienced male discrepancy stress were nearly three times more likely to have committed violent assaults with a weapon or assaults resulting in injury to the victim than those who didn't worry about it.

There was no association between discrepancy stress and daily use of alcohol or drugs, but men who felt less masculine, and who were not worried about it, were the least likely to report violence or driving while under the influence.

"This may suggest that substance use/abuse behaviours are less salient methods of demonstrating traditional masculinity in contrast to behaviours related to sex and violence, perhaps due to the potentially private nature of the habit," suggest the researchers.